Reactor and method of operating same



May 27, 1958 R. R. GolNs 2,836,636

REACTOR AND METHOD OF OPERATING SAME.

Filed June '7. 1954 2 Sheeffs--Shee'I 1 May 27, 1958 R. R. GOINs REAcToR AND METHOD oF OPERATING SAME 2 Sheets-Sheet 2 Filed June 7. 1954 STEAM 9 4 lll 42 FUEL GAS f @win- 1? D f ITV/ 6 MYMQT.

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TIMER MOTOR AIR UNDER PRESSURE INVENTOR.

R.RGO|NS United States Patent@ REACTGR AND METHD F OPERATING SAME Robert R. Goins, Bartlesvilie, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware 4.application Jane 7, 1954, serial No. 434,955 17 Claims. (C1. 25a-'679) This invention relates to regenerative `furnaces and to la novel method of operating such regenerative furnaces.

ln another aspect, it relates to a novel retractable nozzle system.

In regenerative furnaces, a stream of air and fuel gas is burned in, or hot combustion products passed through, a refractory checkerwork, thereby heating it to a high temperature. After the hot gases have passed through the checkerwork for a time sufficient to heat it to the desired temperature, the flow of combustion gases is terminated, and thereafter the reactants to be treated are passed through the heated checkerwork to bring the gases to reaction temperature.

In a particularly useful furnace of this type utilized for the cracking of hydrocarbons, such as methane, ethane, propane or butane, to produce unsaturated hydrocarbons, such as acetylene or ethylene, a central Vcombustion zone is provided with an elongated checkerwork of refractory material at either end ofthe combustion` zone. Air is passed in one direction through one of the checkerwork structures, while a fuel gas is introduced into the combustion chamber. The fuel gas and air mixture thus produced is burned and heats up the refractory checkerwork downstream of the zone of fuel introduction. v

When this checkerwork has attained a suiciently high temperature, the flow of air and fuel is stopped, and the material to be cracked or otherwise converted passes in the opposite direction through the heated checkerwork to the reaction zone where the desired cracking or other reaction takes place.

After a timed reaction period, the ow of reactants is stopped, and air is passed through the checkerwork in a direction opposite to that of its first introduction. At the same time, fuel gas is introduced into the combustion zone to mix with the air and form a combustible mixture which is burned in the combustion zone and the refractory checkerwork section downstream of the combustion zone to heat this section of checkerwork. When the last-mentioned checkerwork section obtains a suciently high temperature, the feed to be converted passes through the heated section to convert or crack same.

I have discovered that the operation of regenerative furnaces, and particularly regenerative furnacesrof the character just described, can be substantially improved by providing uniform distribution of the fuel gas across the cross-sectional area of the combustion zone during the period when this fuel .gas is mixed with air and burned to heat one or the other of the refractory'checkerworks. it is of particular advantage to introduce the fuel gas through a series of retractable nozzles so arranged that, in their extended position, a uniform distribution of the fuel gas is obtained throughout the cross-sectional area of the combustion chamber. When the heating period has been terminated'7 the retractable nozzles are withdrawn, to the end that they do not interfere with the succeeding/cracking or other conversion action tal;L

ing place in the reaction zone and, by being withdrawn,- the nozzles are protected from the high temperatures' normally encountered in the combustion zone asthecori= version reaction takes place. 4

lt is a feature of the invention that the retractable, nozzles are of novel construction, therretr'acting and ex-v tending mechanisms being operatively connected to and cooperating with the control system regulating the ow of fuel gas, air, and reactants to the furnace. Thus, a special ,coaction and cooperation exists betweensthe re-YV tractable feed nozzles and the furnace incorporating a combustion zone with two longitudinally-extending@ checkerworks. However, as will become apparentfrom the following description, certain features of'construc-- tion and operation of the nozzles have independent utility in other types of regenerative furnaces, and in evenother y types of reaction vessels where cyclically-varying operations take place.

It is an object of the invention to provide an improved regenerative furnace and associated apparatus.

it is a further object of the invention to provide an f improved method for operating a regenerative furnace.;A

lt is a still further object of the invention to provide retractable nozzles cooperating with the constructionand .v

control features of a regenerative furnace having a central combustion zone with two sections of refractory checkerwork extending longitudinally therefrom.

It is a still further object of the invention to provide f retractable nozzles of novel construction having varying applications in furnaces and other types of reaction e and Figure 5 is a view illustrating a feature of construction of the checkerwork.

Referring now to the drawings in detail, and particularly to Figures 1 and -5, I have shown a regenerative furnace iti including a central combustion zone 11 of rectangular cross section having elongated checkerworks 12 and 13 communicating with opposite sides of the combustion zone il, the checkerworks and combustion zone` being enclosed within a shell 14 of refractory material. Preferably, the entire furnace is of rectangular cross section, and the insulating shell 14 can advantageously be formed from two distinct layers of re brick, the inner layer having more refractory characteristics than the outer layer. The entire furnace is enclosed WithinV a steel shell 14a.

The checkerworks 12 and 13 are formed from refractory tiles i5 and 16, Figure 5, which are arranged within the furnace with their longitudinal axes extending trans; versely thereof. It will be noted that the edgesI of the tiles have spaced semi-circular cutout portions formed therein which cooperate, when the tiles are laid on top of each other, to form a series of openings 17 which extend longitudinally, Figure 1, from the respective ends of the furnace to the facing surfacesdelining the com` bustion zone 11.

. In Certainrfurnaesof thistype, nhichhave been found- 1';

operating system for the retractable nozzle of Figure 3;

useful for fthe production of acetylene, the reaction zone was 9" wide and 20 high, the total furnace length Vbeing 9'41/2" with a combustion chamber length of 9". In ay commercial furnace, suitable dimensions would be a cross section of 257" x '80, for the reaction zoneiwith a combustion zone length of and a'total furnace length of approximately 16'. The proper dimensions, of course, vary with the exact throughput of the furnace, the type of reactants used, the temperature and pressure necessary to effect the desired reaction, and various other operatingfeatures.

Further, in some furnaces of this type, there are two gasA distribution chambers closely spaced to the combustionchamber and Vseparted therefrom by a 'short section of checkerwork or refractory tiling. Finally,'the nature and type' ofconstruction of the cheokerwork varies considerably from installation to installation depending upon `the temperatures required for effecting the desired conversion or cracking reaetiointhe type of fuel used, andthe time necessary for the process and regeneration cycles.

In the furnace shown by Figure l, which is suitable particularly for the producti-on of acetylene from natural gas vory propane, yor the'formation of ethylene from butane, the feed material isintroduced, together with steam, if`desired, into a conduit 2l), Figure l. Conduit 20 is connected 'by a three-way valve 21 to a conduit 22 which, in 'lt-urn, is`connected through a three-way valve 23 to a conduit 24 communicating with the checkerwork 13 adjacentv the end `of the furnace or, alternatively, with a Aconduit 25 vwhich is connected to the checkerwork 12 Vadjacent the end of the furnace."V Each of the conduits 24, v25 communicates with its respective checkerwork 12 or 13 through a distributor box 26 which can be provided with a distribution plate 27 to facilitate even distribution. of the material across or throughout the crosssec'tional area of the checkerworlri,V

The threeeway valve 21 is alsofoperative to connect an air conduit 28 with conduit 22and, thence with conduit 24 or 2'5, as determined by the setting of valve 23. Conduits 24 and 25 are also selectively connected by a three-way valve Sti to anV eti'luent conduit 31 which leads toa product recovery system 32?., or other disposal, as desired. v l f Y As will be explained in detail hereinafter, valves 2l, 23 and Stlare operatively connected to a sequence timer 33 to provide alternate regeneration and process cycles. Alternate heating" cycles are carried out to, in succession,

Y cap 39e and communicating with the interior of the `nozzlev 39. The pipe is journalled in a suitable bearing 41 formed in a reducedinner'end of the pipe 38, andV with the rack 43 is a pinion 45 which is connected tothe shaft of aV reversible motor 46.- It willbe apparent that rotation of motor 46 in one direction extends the nozzle'interiorly of the combustion zone whilel rotation 0f the motor in the opposite retracts the nozzle 39 so that it is positioned within the pipe 38. Travel of the nozzle is limited lbetween the desired extended and retracted positions by stops 47 and 48,

Purge steam is admitted through a valved line 49jto the interior of pipe 38, this purge steam being admitted during the period when the nozzle isretracted to prevent any Vof the material in combustion zone 11 entering the nozzle structure.

Referring now to Figure 2, it will 'be noted that the steam lines 49 of all the nozzle assemblies 35 are connected to a common headerY 50, the supply steam to this headerY being controlled by a( solenoid valve 51. Operationof solenoid valve 5,1, in turn, is controlled byk a cam SZAmounted on a camshaft 53 whichV is driven by a timer motor 54Y forming a part of thesequencetimer Y 33, Figure l.

heat the refractory chec'kerworks 12 and 13 to the desired temperature suitable for the forthcoming flow of reactant material therethrough.

In accordance with the Vinvention,'a series of retractable nozzle `assemblies'35u! to 35e is provided, one set at each sideof the combustion zone 11. Althoughfive such nozzles havev been illustrated, as will Abecome apparent.V

hereafter, the Ynumber jcan be varied, as desired, to en- Referring to Figure 3, each nozzle extends through a i horizontal opening 37 formed in the refractory shell le,V this -opening being provided Ywith a tube or pipe 33 of refractory metal firmly securedrin position within` the opening 37 by flanges 38a and SSb. Slidably mounted within the pipe 3S isa pipe or nozzle 39 having a series of spaced openings 39a preferably Vformed in the top and bottom thereof, the lengthV of the pipeV in which the openings are formed preferably being Vabout half of the width of theeombustion zone 11. A

The ends of pipe or nozzle 39 are closed by end caps 39h-and 39C, asection'offpipe 40 being secured to Vend In similar fashion, thef-u'el gas lines 42 of all the noz-` zle assemblies 35 are connected to a common header. 56, the supply of fuel gasto which is controlled by a solenoid valve 57 -operated by a cam 58 on camshaft 53. Each of the reversible mA-,ot'ors46 is provided with two windings which are connectedto common leads 60 and 61. These are rconnected selectively to ground under the controliof cams 62 and 63, respectively, mounted on earnV shaft 53.. VGrounding of lead 60 causes the motors to rotate in one direction and retract all of the nozzles 39 of the respective assemblies V35 `while grounding of lead 61causes operation of the motors ini the opposite 4direction tomove the ,n'ozzles toY their extended positions within the reaction chamber. The( three-way valves 21, 23 and 30 are all of the solenoid type, and their action is controlled in the manner hereinafter described by cams 65, 66 and 67, respectively, carried by the cam shaft 53.V

' yThe over-all operati-on of the system will now be apparent toithose skilled in theV art. Y In an initial position, the nozzles 39 are all in an extended position in the combustionzone 11, i. e., the switch associated with cam 63Y is closed'and that associated with cam 62 is open. At

this time, under the control of the cams, valve 57 is`open andV valve 51 is closed so that fuel gas flow-s through the retractable` nozzles, and no purge steam is admitted to the pipes 38. Valves' 21 and 23 are in suchV position that Y Vair is -fedthrough conduit-s 218, 22 and 25.to the checki erwork 12, the air pas-sing therefrom'into the combustion zone y11 where it is mixed with fuel gas from the re-V tractable nozzles, the resulting mixture being ignitedand l pair of nozzles Vat `the saine level in thel combustionzoue extends practically` half way into the combustion vzoneV so that theopenin'gs 39a in these nozzles extend ,substantially uniformly throughout the width of the combustion of subsantially uniform composition throughout the crossl Alternatively, valve 51 can he y to the low temperature of the entering air passing through checkerwork 12, and the temperature of the flame which, however, is carried downstream of the nozzles by the passage of air through the system. As a result, the nozzles, in their extended positions, are not subjected to excessive temperatures. They can, of course, be steam jacketed if they are not kept suiciently cool by the fuel gas passing through them.

At the conclusion of a predetermined length of time, as determined by the speed of rotation of timer motor 54 and the congurationof the cams on shaft 53, valve- 21 is actuated by the movement of cam 65 to transfer conduit 22 from its connection with conduit 2S to a connection with conduit 20. This causes steam and feed to pass through conduits 22, 24, the heater refractory checkerwork 13, combustion zone 11, refractory checkerwork 12, and conduits 25, 31 to the product recovery system 32. Simultaneously with the described movement of the valves 2l, 23 and 30, cams 52, 58, 62 and 63 are actuated, thereby operating motors 46 to retract the nozzles 39 into the walls of the furnace and out of the combustion zone 11. Also, valve 57 is closed, thus interrupting the supply of fuel gas through header 56 to the gas supply lines 42, and valve 51 is opened to admit purge steam through header 50, lines 49, and the conduits 33 of the respective nozzle assemblies 35. The nozzles are, therefore, moved out of the combustion area.

The reaction zone is advantageously Voperated at a high cracking temperature in the range of l850 F. to 1900 F. where the feed consists of 30G standard cubic feet per minute of propane, 1.75 volumes of recycle gas, containing ethylene, carbon dioxide and a small amount of diacetylene together with 6 to S volumes of steam per volume of propane. These conditions are typical for operation of a furnace utilized to crack propane to form acetylene. Of course, the furnace is also suitable for other reactions, such as the cracking of butane to form ethylene, thermal cracking of gas oils, and various other reactions, particularly those carried out at a high temperature.

As stated, with the nozzles retracted into the walls of the furnace, they are not subjected to the high temperatures existing within the reaction zone, and they are further protected from this high temperature, and from contact with the reaction products, by the purge steam admitted through a line 49 to each of the pipes 38 of the respective nozzle assemblies.

After a suitable time, one minute being a suitable reaci tion period and regeneration period for the cracking of propane to form acetylene, the cams on shaft 53 again actuate valves 21, 23 and 30 to cause air to pass through conduit 28, conduit 22, and conduit 24 to the checkerwork 13, whence it passes through combustion zone 11, refractory checkerwork 12, conduit 25, and conduit 31 to the product recovery system 32, where it is utilized for heat exchange or other suitable purposes. Such operation of valve 21, of course, closes off the supply of steam and feed through conduit 20. At the same time, cams 52, 58, 62, and 63 are actuated to interrupt the supply of purge steam to the nozzle assemblies, effect operation of motors 46 to move the nozzles to their extended positions within the combustion zone, and supply fuel gas to the nozzle assemblies 35, whereupon the fuel gas and air are mixed to form a combustible mixture which is burned in refractory checkerwork 12 until this checkerwork is heated to the desired extent, for example, for a period of one minute.

Thereupon, valves 21, 23 and 33 are again actuated by cams 65, 66 and 67 to pass steam and feed from conduit 20 through conduit 22, conduit 2S and checkerwork 12 to the reaction zone 11. The converted products pass from the reaction zone through checkerwork 13, conduit 24 and conduit 31 to the product recovery system 32. Cams 52, 58, 62 and 63 are again actuated to supply purge steam to the pipes 38 Vof therespective: nozzle units, the supplyhf fuel gas is shut olf through closure of valve 57, and the nozzles are retracted byV the action of one or more motors 46. At the end of this second reaction period, cam shaft 53 assumes its original position in readiness for a new cycle of operation with air passing at a leftward direction, Figure 1, through the furnace, fuel gas passing through the extended nozzles 35 to the combination zone 11, and the supply of purge steam cut olf.

It will be apparent, therefore, that l have achieved the objects'of'the invention in providing a Vregenerative furnace of novel construction wherein a uniform distribution of fuel gas is obtained across the cross sectionlof the furnace during the regeneration cycle, with resultant thorough mixing of the fuel gas with air to provide Aa combustible mixture. This results in a uniform tempe'rature across the cross section of the furnace, which greatly improves the cracking or other reaction. Further, the novel retractable nozzle assemblies cooperate with the elements of the furnace to the end that they are withdrawn during the reaction period so they are not exposed to the high reaction temperatures, purge steam being admitted to prevent contact of the reaction product with the nozzles in their retracted position and to further protect the nozzles against the high reaction temperature. Finally, the operation of the nozzles is conveniently tied in with the automatic control system automatically operating the furnace to provide the proper reaction and regeneration cycles. It will also be evident that the retractable nozzle assembles are of novel construction, and have independent application in other types of furnaces and reactors, although there is a special cooperation between the nozzle assemblies and a furnace of the type described herein. p v

in Figure 4, I have shown a modification of the nozzle assemblies whereby the nozzles are extended and retracted pneumatically. In this ligure, pipe 40 is secured to a rod 75 carrying a piston i6 which is slidable within a piston chamber 77, the piston being provided with a sealing gasket 78. Ports are provided at the respective ends of the piston chamber which communicate through conduits 79 and S2 with a four-way valve St), an exhaust line 81 and an air supply line S3. It Wlil be evident that, with the valve 80 in the position shown air is supplied to the piston chamber in such fashion as to move the .piston in a rightward direction, Figure 4, and retract the nozzle. With valve 80 in its second position, (rotated counterclockwise, Figure 4) conduit 79 communicates with exhaust line 81- and conduit 82 communicates with pressure supply line 83 to the end that the piston is moved in a leftward direction, Figure 4, and the nozzle is extended into the reaction chamber. Valve 80 is a solenoid valve which is controlled, to extend and retract the nozzles, in a manner similar to that described iu connection with the operation of Figures l, 2 and 3 under the Vcontrol of a cam, such as cam 62, mounted on the camshaft 53. Accordingly, where the system of Figure 4 is used, the nozzles are extended and retracted pneumatically, the operation of the system being Otherwise the same.

While the invention has been described in connection with a present, preferred embodiment thereof, it is to be understood that this description is illustrative only and is not intended to limit the invention.

I claim:

l. In combination, a reactor vessel having a shell, said shell having an opening formed therein communicating with the interior of said reactor, a perforated nozzle slidable within said opening and movable between an extended position where the nozzle is positioned within the reactor and a retracted position wherein the nozzle is p ositioned within said opening, means sealing the outer end of said opening, a bearing formed in said sealing means, an actuating member extending through said bearassenso inglhd lconnected to said nozzle, meansgfoi effecting longitudinal movement, with respect t'o said opening, of

said actuating member thereby to extend and retractsaid nozzle, means for feeding material through said nozzle,

Va'ndrneans'for passing a purging fluid throughV 'said sealing Vmeans and said opening. into the reactor. Y

V2.' ln combination, ak reactor vessel having a shell,

Ysaid shell having an opening formed therein communieating WiththeV interior lofY saidV reactor, al perforated nozzle slidable within said opening 'and movable between an extended position where the nozzle isrpositioned Within the 'reactor and a 'retracted'position kwherein the nozzle isk positioned within said opening, means sealing Ythe outer end lof said opening, ajbe'aring formed in said sealing means, an actuating memberextending through said 4bearing and connected to. said nozzle; a rack se-VV cured to said actuating member, a pinionrmeshingrwith said rack, means'rfor rotatingsaid pinion to effect longi- V ltldinal movement of the rack` and actuating member, Vthereby to extend and retract'said nozzle, means for feeding material through Vsaid nozzle,fand Vmeans` for passing a purging iluidcthrough lsaid sealing means and said opening into the reactor. f

3. in combination, a reactor vessel having a shell, said shell having an opening'formed therein communicating with the interior of Vsaid reactor, `a perforated nozzle slidable Within said opening and movable Vbetvveenan extended position where the nozzle i's positioned Within the reactor and a retracted positionV `Jvherein the nozzlek is positioned Within said opening, means sealingV the outery end of said opening, a bearing formed in saidV seallng means, an actuating member extending through said'bearing and connected to said nozzle, a piston chamber,V aV

piston movable longitudinally within said chamber, a piston rod carrying said piston andr'secured to said actuating member, means for supplying ,pressure uidto the piston chamber to effect longitudinalmovement of the piston 4and actuating rod, thereby to extend and retractV said nozzle, means for feeding material through said nozzie, and means for passing a purging fluid through'` said sealing means and said opening into the reactor. j 4. in combination, a reaction vessel having a refractory shell, said shell Vhaving an elongated opening formed ,therein yextending from the interior to the exterior thereof, a pipe or sleeve secured'to said shellan'd extending through said opening,means `for sealing thefend of said sleeve adjacent the outer lend of said opening, a bearing passing air through -said combustion zone into said check erwork, means for passing material to be convertedY lthrough said' vchecloerwork VVinto ithe 'combustion zone, a

pluralityof elongated nozzles protrudingfinto said come bustion Vzone through said refractorymaterial, eachnozzle being provided with a set of longitudinallyfspfaced`V discharge openings, Vsaid Vnozzles being arrangedY about Vthe combustion zone yjs'o that the discharge openings provide a substantially!uniform'distribution of materialissuing therethrough across fthe'fcross-sectional area of the combnsti'on zone, means for admitting purge steam to .the

combustion zone through a circumferential path fsurrounding each nozzle, andV means for retracting said Vnozzles intoV said refractory material vtoY remove .themV from'the vcombustion zone.V Y

9, A regenerative Yfurnace comprising, incombination, anelo'ngated refractory checkerwork, refractory insulating materialdefining a combustion zone communicating with one. end of said refractory checkcrWork, means for formed in said sealing means, means for admitting a purging medium to the interior of said sleeve, Vak pipe extending through said bearing into'said sleeve, an elongated'nozzle secured to said pipe and communicating of longitudinally spaced openings formed Vat Vthe interior endthcreof, means for supplying fluid to said pipe and thereby to said nozzle, and means for effecting longitudinal movement of said pipe, thereby to move said Vnozzle between a rst position Where said interior end protrudesY the nozzle is positionedwithin said sleeve.

5. A reaction vessel constructed in Vaccordance with claim 4 wherein said last-mentioned means includesa intoV the reaction vessel Vand a retracted position Where passing air through saidV combustion zoneV into said checkerWork, means rfor Vpassing .material to beconverted through .said checkerworlr into the combustion zone, a plurality of Vnozzles protruding into said combustionzone throughY said refractory material, means for supplying fuel Ygas to 'said nozzles, means forretrac'ting said Vnozzles into said refractory material and `thereby removing'them Y from the combustion zone, andA means for admitting purge steam to the 'combustion zone through a circumferential path surrounding'each nozzle. y l0.A In av regenerative furnace, inV combination, a mass of refractory material `constructed and arrangedto deline -a'cornbustion zoneof 'rectangular cross 'sectionr a Vlongitudinallyfextending refractory checkerwork communicating with one end of said combustion zone, a

longitudinally-extending refractoryV checkerworkv communicating with the other endofsaidcombustionzone,

. meansrfo'rsequentially admitting air and material to be Y with the interior of said pine, said nozzle having a set` rackfs'ecured'to said pipe, a pinion meshing VAwith said ra'ck,'and a motor connected tosaid pinion Vto rotate samel and thereby eect said longitudinal movement.

6. A reaction vessel in accordance with claim` 4 in which the last-mentioned means includes a piston chamber, a piston movable therein, a piston 'rod secured to said piston and connected to said pipe, and means for admitting pressure fluid to the piston chamber to effectV said longitudinal movement of the pipe, and thereby of the nozzle. Y

7. A regenerative furnace comprising, in combination,

an elongated refractory checkerwork, refractoryV insulating material defining a combustion zone communicating with one end of said refractory checkerwork, means for converted to the ends of said refractory .checkerworks remote `from said combustion zone, a pluralityof nozzles protruding into said combustion zone through said refractory material, means lfor supplying fuel gas to said l' Y nozzles, and means-for retracting said nozzles into said 'refract'my material and thereby removing 'them from the combustion zone. j

11. in a regenerative furnace, `in combination, a Amass of refractory material constructed` and arranged to denne a'cornbustion zone of rectangular cross section, a longitudinally-extendingV refractory checkerwork communicating with one end of said combustion zone, a longitudinallyextending refractory checkerwork communicating with the other end Vof said combustion zone, means for ;sequentially admitting air and materialto be converted Vto Vthe ends of said refractory checkerworks remote from said combustionzone, a plurality of elongated nozzles protruding into said combustion zone throughV said refractory material, each nozzle being provided With a set of lon-k gitudinally-spaced discharge openings, said nozzles `being arranged about the combustion zone so that the discharge openings provide a substantially uniform distributionof material issuing therethrough across the cross-'sectional area of the combustion zone, means for admitting purge Y steam Ytothe combustion zone Ythrough aY circumferential Y '15 path surrounding each nozzle, and means for retracting said nozzles into said refractory material to remove them from the combustion zone.

12. In a regenerative furnace, in combination, a mass of refractory material constructed and arranged to dene a combustion zone of rectangular cross section, a longitudinally-extending refractory checkerwork communicating with one end of said combustion zone, a longitudinallyextending refractory checkerwork extending to the other end of said combustion zone, a conduit for supplying material to be converted, an air supply conduit, an effluent conduit, valves connecting said conduits to the respective ends of said refractory checkerworks remote from said combustion zone, the refractory material defining two opposite sides of said combustion zone having a series of longitudinally-spaced openings formed therein disposed in a plane generally perpendicular to the longitudinal axis of the furnace and approximately at the center of said combustion zone, an elongated retractable nozzle slidably mounted within each of said openings, said nozzles being arranged to extend into the combustion zone and provide a pattern of material discharged therethrough which is substantially uniform across the cross-sectional area of the combustion zone, a source of `fuel gas, valve means controlling supply of said fuel gas to said nozzles, means for moving said nozzles from said extended position to a retracted position where they are positioned within said openings, a source of purge steam Valve means admitting purge steam to the openings around said nozzles, and a sequence timer operatively connected to said valves and said valve means to provide alternate process and regeneration periods, said timer cooperating With said valve means to extend said nozzles, supply fuel gas thereto, and interrupt the supply of purge steam during regeneration periods and retract said nozzles, interrupt the ow of fuel gas and supply purge steam during process periods, said sequence timercooperating with said Valves to admit air to the ends of said refractory checkerworks remote from the combustion zone in alternating fashion during successive regeneration periods, and said sequence timer cooperating with said valves to admit feed to alternate ones of said refractory checkerworks during alternate process periods.

13. A regenerative furnace in accordance with claim 12 in which the refractory checkerworks comprise elongated refractory tiles having a series of semi-circular recesses formed in each longitudinal edge thereof, said tiles being laid so as to provide a multiplicity of cylindrical passages extending longitudinally of said refractory checkerworks.

14. A process for effecting a high temperature reaction which comprises passing air in a longitudinal path through a combustion zone and then through a refractory checker- Work, discharging ya fuel gas to said combustion zone at a multiplicity of locations arranged uniformly across the cross-sectional area of the combustion zone to form a combustible mixture of substantially uniform composition throughout its cross section, burning the thus produced combustible mixture in said refractory checkerwork to heat same, interrupting the described ow of fuel gas and air, passing material to be converted through the thus heated refractory checkerwork and thence, in an unobstructed path, through the combustion zone to effect the desired reaction, and withdrawing converted material from said combustion zone.

15. A process for conducting high temperature reactions which comprises passing air, in a longitudinal path, through a rst refractory checkerwork, a combustion zone, and a second refractory checkerworlc, introducing fuel gas into said combustion zone at a multiplicity of regions substantially uniformly arranged across the cross section of said combustion zone normal to the path of air flow, thereby forming a combustible mixture of uniform composition throughout its cross section, burning said combustible mixture in the second checkerwork to heat same to a desired temperature, interrupting the ow of air and fuel gas, passing material to be converted through the second checkerwork, then in an unobstructed path through the combustion zone, withdrawing the effluent through said first checkerwork, interrupting the ow of material to be converted, passing air in a longitudinal path through the second checkerwork, the combustion zone, and the first checkerwork, admitting fuel gas to the combustion zone at a multiplicity of regions spaced substantially uniformly across the cross section of the combustion zone normal to the air flow to form a combustible mixture of substantially uniform composition throughout its cross section, burning said combustible mixture in said first checkerwork to heat same to a desired temperature, interrupting the flow of gas and air, passing material to be converted through said first checkerwork and, thence, in an unobstructed path through the conversion zone to effect the desired conversion reaction, and withdrawing the reaction effluent through said second checkerwork,

16. The process of claim 15 wherein the material to be converted is propane and the conversion reaction is the cracking of propane to form acetylene.

17. The process in accordance with claim l5 in which the material to be converted is butane, and the conversion reaction is the cracking of butane to form ethylene.

References Cited in the le of this patent UNITED STATES PATENTS 1,714,232 Morris May 21, 1929 1,925,338 Franke Sept. 5, 1933 2,475,093 Hasche July 5, 1949 2,518,239 Leigh Aug. 8, 1950 2,678,339 Harris May 11, 1954 2,692,131 Hasche Oct. 19, 1954 2,692,456 Dauncey Oct. 26, 1954 2,692,819 Hasche et al. Oct. 26, 1954 FOREIGN PATENTS 583,851 Germany Sept. 13, 1933 

1. IN COMBINATION, A REACTOR VESSEL HAVING A SHELL, SAID SHELL HAVING AN OPENING FORMED THERIN COMMUNICATING WITH THE INTERIOR OF SAID REACTOR, A PERFORATED NOZZLE SLIDABLE WITHIN SAID OPENING AND MOVABLE BETWEEN AN EXTENDED POSITION WHERE THE NOZZLE IS POSITIONED WITHIN THE REACTOR AND A RETRACTED POSITION WHEREIN THE NOZZLE IS POSITIONED WITHIN SAID OPENING, MEANS SEALING THE OUTER
 14. A PROCESS FOR EFFECTING A HIGH TEMPERATURE REATION WHICH COMPRISES PASSING AIR IN A LONGITUDINAL PATH THROUGH A COMBUSTION ZONE AND THEN THROUGH A REFRACTORY CHECKERWORK, DISCHARGING A FUEL GAS TO SAID COMBUSTION ZONE AT A MULTIPLICITY OF LOCATIONS ARRANGED UNIFORMLY ACROSS THE CROSS-SECTIONAL AREA OF THE COMBUSTION ZONE TO FORM A COMBUSTIBLE MIXTURE OF SUBSTANTIALLY UNIFORM COMPOSITION THROUGHOUT ITS CROSS SECTION, BURNING THE THUS PRODUCED COMBUSTIBLE MIXTURE IN SAID REFRACTORY CHECKERWORK TO HEAT SAME, INTERRUPTING THE DESCRIBED FLOW OF FUEL GAS AND AIR, PASSING MATERIAL TO BE CONVERTED THROUGH THE THUS HEATED REFRACTORY CHECKERWORK AND THENCE, IN AN UNOBSTURCTED PATH, THROUGH THE COMBUSTION ZONE TO EFFECT THE DESIRED REACTION, AND WITHDRAWING CONVERTED MATERIAL FROM SAID COMBUSTION ZONE. 